Applicant is aware of the following U.S. patents:
______________________________________ Patent Reg. No. ______________________________________ Electric Circuit Connection 501,631 for Signaling or Telephone Boxes Police Patrol Signal Box 542,074 Alarm Box Attachment 870,963 Signaling Mechanism 1,616,879 Door for Fire Alarm Boxes 2,000,517 and the Like Signal Station 3,183,501 Fire Protection Apparatus 4,162,485 Fire Alarm Signal Station 4,280,120 ______________________________________
The disclosures of the above patents are incorporated herein by reference.
This invention relates generally to remote signaling devices which permit an alarm to be initiated at various locations. Signaling boxes are well known in the art and are generally used so that a person who discovers an emergency, such as a fire, can promptly signal assistance.
One of the characteristics of these signaling boxes is a means to avoid inadvertent operation of the alarm. Some prior devices have used a sheet of single strength glass placed over the switch to prevent inadvertent operation. There are several difficulties with using these devices. First, a striking instrument, such as a hammer must be provided in order to break the glass. Even though the hammer is attached by a chain, it is very often missing or stolen. Second, the breakage of the glass is dangerous. Even though warnings are placed near these boxes, accidents may occur in which the glass shatters into the eyes of the person activating the alarm. Also, the switch cannot be reset into a non-alarm condition until the glass is replaced. Finally, the glass cover can be accidentally broken easily in high traffic, commercial or industrial areas.
Some devices have attempted to deal with the problem of breaking glass by substituting a glass rod on the inside of the box to prevent activation of the switch. This does not solve the problem of replacing the glass after the alarm has been activated. Further, broken glass must still be cleaned up and disposed of after activation of the alarm.
Signaling boxes which do not have glass generally limit access to the switch through use of a door cover. For example, one arrangement is to place a door cover directly over the switch or activator. The problem with this arrangement is that even though this will limit the access to the switch, the door cover does not prevent the activation of the switch. In another arrangement a glass rod (similar to that mentioned above) is used to prevent opening of the door cover. This arrangement retains the problem of broken glass disposal.
None of the above arrangements provide a quick method of returning the device to a normal condition. Most of the devices require replacement of a glass sheet, glass rod or the like. In certain applications, alarm conditions occur very frequently. For example, in chemical laboratories or manufacturing, fires may routinely occur. Replacement of the glass parts each time an alarm occurs is time consuming and expensive.
Another problem with signaling devices is interference by foreign objects with operation of the switch. For example, one prior device leaves the switch exposed on all sides. This exposure permits particles from manufacturing and other foreign matter to interfere with operation of the switch. Unless there are routine tests of the alarm device, these particles may prevent operation of the device.
This invention solves these and other problems. Applicant has developed a signal box having no glass parts. When the door cover is closed, a stud mounted on the cover prevents activation of the alarm switch. In this closed position a sliding panel retains a spring-loaded activator in a depressed non-alarm position. The interaction of the sliding panel and the stud on the cover provides foolproof interlocking since opening the cover does not operate the activator. This foolproof interlock results in a two step operation, as discussed later, in order to put the signal box in an alarm condition. Because the cover is made of non-breakable material, the chance of inadvertent or accidental activation is minimized. The door cover is also solid on all sides to prevent interference from foreign material.
Two steps are required to activate applicant's alarm switch, a further assurance against inadvertent activation. First, the door cover must be pivoted to an open position. This step removes the stud from the sliding panel, but does not activate the switch. Second, a pull ring, attached to the end of the sliding panel, is used to pull the sliding panel down to a signaling position. In this position the spring-loaded activator is released into an opening in the sliding panel allowing a switch to operate.
The resetting of the signal box is very simple and does not require the replacement of any parts. First, the activator is held in the depressed position by finger pressure. The sliding panel is then returned to its normal position in which the activator is retained in the depressed position. The door cover can then be closed so that the stud is inserted in an opening in the sliding panel and prevents the sliding panel from moving downward.
These and other objects and advantages will be apparent from the drawings and descriptions as follows.